The present invention relates to a portable terminal apparatus for an IC card which can selectively read out various transaction data and amount data from the IC card for use as a credit card and electronic money, and display them.
Recently, those IC cards serving as a hand-held storage medium and including an IC chip having a nonvolatile memory and control element, such as a CPU (central processing unit) for controlling associated component parts have been utilized in various sectors of industry.
This type of IC card, such as a credit card and electronic money, proves very useful if various kinds of transaction data, amount data, etc., stored therein can be read out if necessary and displayed.
Recently, in order to achieve such an object of the present invention, a portable terminal apparatus for an IC card has been developed which can be carried at all times with the user. The portable terminal apparatus is formed to have a card-like configuration. The apparatus includes a keyboard, liquid crystal display unit and battery for its own use and for a power supply to the IC card. With the IC card inserted, it selectively reads out the various transaction data and amount data, in accordance with a key operation on its keyboard and displays them.
In such portable terminal apparatus, an internal circuit has conventionally been operated with a signal voltage supplied to the IC card. Further, in the case where key matching is to be done, password data for key matching is input to the apparatus after the IC card has been duly activated.
In the case where the data is read out of the IC card, first the IC card is activated and corresponding data is read out and displayed. Until the display is finished, the IC card is kept ON and then deactivated when the display is finished. Since, therefore, the IC card is supplied with an electric current during its activation, the efficiency of a dissipation current is poor.
In the case where an error is generated when reading data out of the IC card, a corresponding error message is displayed and then deactivated. For this reason, until the display is finished the IC card stays activated and, during the activation, electric current flows through the IC card. As a result, the efficiency of the dissipation current is poor.
In order for the conventional portable terminal apparatus to be made compact in size and low in cost, it is necessary to reduce the size and capacity of a battery serving as a power supply. However, there is a limit that the operation voltage of an associated internal circuit is made equal to that of the IC card.
Further, with the IC card activated, a power supply voltage is kept supplied to the IC card. In the case where the password data is input from an outside source, if there is either a wait or password data to be input or no data is input to the apparatus, dissipation current continues to flow over a predetermined time period. For this reason, the dissipation current becomes very large and the life of the battery, that is, a power supply, is shortened. That is, the longer the access time of the IC card, the shorter the battery life.